Multilayer ceramic capacitor, ceramic powder, manufacturing method of multilayer ceramic capacitor and manufacturing method of ceramic powder

Abstract

A multilayer ceramic capacitor includes: a multilayer structure in which ceramic dielectric layers and internal electrode layers are alternately stacked, wherein: a main component of the ceramic dielectric layer is barium titanate in which a donor element having a larger valence than Ti is solid-solved and an acceptor element having a smaller valence than Ti and larger ion radius than Ti and the donor element is solid-solved; a solid-solution amount of the donor element is 0.05 mol or more and 0.3 mol or less on a presumption that an amount of the barium titanate is 100 mol and the donor element is converted into an oxide; and a solid solution amount of the accepter element is 0.02 mol or more and 0.2 mol or less on a presumption that the amount of the barium titanate is 100 mol and the acceptor element is converted into an oxide.

What is claimed is: 
     
         1 . A multilayer ceramic capacitor comprising:
 a multilayer structure in which ceramic dielectric layers and internal electrode layers are alternately stacked,   wherein:   a main component of the ceramic dielectric layer is barium titanate in which a donor element having a larger valence than Ti is solid-solved and an acceptor element having a smaller valence than Ti and larger ion radius than Ti and the donor element is solid-solved;   a solid-solution amount of the donor element with respect to the barium titanate is 0.05 mol or more and 0.3 mol or less on a presumption that an amount of the barium titanate is 100 mol and the donor element is converted into an oxide; and   a solid solution amount of the accepter element with respect to the barium titanate is 0.02 mol or more and 0.2 mol or less on a presumption that the amount of the barium titanate is 100 mol and the acceptor element is converted into an oxide.   
     
     
         2 . The multilayer ceramic capacitor as claimed in  claim 1 , wherein the donor element is at least one of Mo and W. 
     
     
         3 . The multilayer ceramic capacitor as claimed in  claim 1 , wherein the acceptor element is Mn. 
     
     
         4 . Ceramic powder comprising:
 barium titanate as a main component,   wherein:   a donor element having a larger valence than Ti is solid-solved in the barium titanate;   an acceptor element having a smaller valence than Ti and larger ion radius than Ti and the donor element is solid-solved in the barium titanate,   a solid solution amount of the donor element with respect to the barium titanate is 0.05 mol or more and 0.3 mol or less on a presumption that an amount of the barium titanate is 100 mol and the donor element is converted into an oxide;   a solid solution amount of the accepter element with respect to the barium titanate is 0.02 mol or more and 0.2 mol or less on a presumption that the amount of the barium titanate is 100 mol and the acceptor element is converted into an oxide; and   relationships y≧−0.0003x+1.0106, y≧−0.0002x+1.0114, 4≧x≧25 and y≧1.0099 are satisfied when a specific surface area of the ceramic powder is “x” and an axial ratio c/a of the ceramic powder is “y”.   
     
     
         5 . The ceramic powder as claimed in  claim 4 , wherein the donor element is at least one of Mo and W. 
     
     
         6 . The ceramic powder as claimed in  claim 4 , wherein the acceptor element is Mn. 
     
     
         7 . A manufacturing method of a multilayer ceramic capacitor comprising:
 synthesizing barium titanate powder by solid-solving a donor element and an acceptor element in barium titanate, the donor element having a larger valence than Ti, the acceptor element having a smaller valence than Ti and having a larger ion radius than Ti and the acceptor element;   forming green sheets with use of the barium titanate powder;   forming a multilayer structure by alternately stacking the green sheets and conductive pastes for forming internal electrodes; and   baking the multilayer structure;   wherein:   a solid solution amount of the donor element with respect to the barium titanate is 0.05 mol or more and 0.3 mol or less on a presumption that an amount of the barium titanate is 100 mol and the donor element is converted into an oxide; and   a solid solution amount of the accepter element with respect to the barium titanate is 0.02 mol or more and 0.2 mol or less on a presumption that the amount of the barium titanate is 100 mol and the acceptor element is converted into an oxide.   
     
     
         8 . The method as claimed in  claim 7 , wherein
 relationships y≧−0.0003x+1.0106, y≧−0.0002x+1.0114, 4≧x≧25 and y≧1.0099 are satisfied when a specific surface area of the barium titanate powder is “x” and an axial ratio c/a of the barium titanate powder is “y”.   
     
     
         9 . The method as claimed in  claim 7 , wherein the barium titanate powder is synthesized by solid-phase synthesizing barium carbonate and titanium dioxide together with the donor element and the acceptor element. 
     
     
         10 . The method as claimed in  claim 7 , wherein the donor element is at least one of Mo and W. 
     
     
         11 . The method as claimed in  claim 7 , wherein the acceptor element is Mn. 
     
     
         12 . A manufacturing method of ceramic powder comprising:
 synthesizing barium titanate powder by solid-solving a donor element and an acceptor element in barium titanate, the donor element having a larger valence than Ti, the acceptor element having a smaller valence than Ti and having a larger ion radius than Ti and the acceptor element,   wherein:   a solid solution amount of the donor element with respect to the barium titanate is 0.05 mol or more and 0.3 mol or less on a presumption that an amount of the barium titanate is 100 mol and the donor element is converted into an oxide;   a solid solution amount of the accepter element with respect to the barium titanate is 0.02 mol or more and 0.2 mol or less on a presumption that the amount of the barium titanate is 100 mol and the acceptor element is converted into an oxide; and   relationships y≧−0.0003x+1.0106, y≧−0.0002x+1.0114, 4≧x≧25 and y≧1.0099 are satisfied when a specific surface area of the ceramic powder is “x” and an axial ratio c/a of the ceramic powder is “y”.   
     
     
         13 . The method as claimed in  claim 12 , wherein the barium titanate powder is synthesized by solid-phase synthesizing barium carbonate and titanium dioxide together with the donor element and the acceptor element. 
     
     
         14 . The method as claimed in  claim 12 , wherein the donor element is at least one of Mo and W. 
     
     
         15 . The method as claimed in  claim 12 , wherein the acceptor element is Mn.